He says the Bill will give union officials unfettered access to workplaces, and employers will have to pass on the details of new employees to unions.

"So they don't even need to ask an employer, they can just go into a workplace to recruit union members. And employers have to pay the union officials to do that."

But the Bill description, headed by Labour MP Iain Lees-Galloway, says its main intention is to "restore key minimum standards and protections for employees".

"The changes are intended to introduce greater fairness in the workplace between employees and employers, in order to promote productive employment relationships."

Mr Lees-Galloway said in January employers have nothing to fear from the Bill.

"The vast majority of employers have not needed to use that provision [not having to conclude negotiations] because they are good employers who want to stay at the table and reach a conclusion," he told NZME.

"The fact only one employer [has] used it speaks volumes as to why we don't need to have it in our legislation."

The concerns marked by Business NZ in a statement are as follows:

The companies that employ most people would not be allowed to use 90-day trials

Breaks for everyone would have to be at the same time unless employees and unions agreed otherwise

Unions could come into the workplace any time they wanted without employer approval, even if there were no union members on staff

If a union wanted a company to join a multi-employer collective, it would be compulsory for the company to join and to reach agreement on the union claims, even for a small business

Companies would not be permitted to offer pay or conditions to an employee on an individual agreement that are different from those offered to an employee on a collective agreement, unless unions agreed

Rules that would make it harder for businesses to restructure.

Measures in the Bill

Guaranteed rest and meal breaks

Ability to engage in low-level industrial action without the threat of pay deductions

The right to the same conditions as other workers on a collective agreement, if you're a new worker

Guaranteed pay and conditions, if you're a vulnerable worker and your employer changes

A requirement to include pay rates in collective agreements

A requirement for employers to pass on information about unions to prospective employees

Greater protections against discrimination on the basis of being a union member

Removing the ability of employers to opt out of multi-employer collective agreements.